This invention relates generally to automated cytological analysis systems and, more particularly, to a method and apparatus for continuous automatic monitoring and forecasting of slide and specimen preparation quality for biological specimen fixed and stained on glass slides.
Detection of disease processes is dependent on adequate specimen collection, proper fixation, staining and mounting of specimens on microscope slides. Laboratory preparation processes can vary over time because variations may occur in specimen collection, fixation, staining and mounting quality for a population of slide specimens. To ensure that slides and specimens are continuously prepared in a fashion which allows for the detection of disease processes, continuous monitoring and forecasting of slide and specimen preparation quality is required.
Standards for the practice of cervical/vaginal cytology have been suggested by the introduction of the well known Bethesda System. However, significant variations in cytological specimens such as, for example, specimens stained with the well known Papanicolaou stain ("pap smears") still occur. Although the pap smear screening process can accommodate slide population, sampling, and preparation variations to some degree, variations that adversely affect the screener's ability to detect the disease process can occur. It is, therefore, important to develop a monitoring process to detect and forecast such variations in order to maintain adequate laboratory preparation for the detection of disease process.
Specimen preparation is monitored periodically by human visual review. This solution has not been satisfactory because the periodic monitoring process is subjective and could suffer from period to period and reviewer to reviewer inconsistency. Also, if a laboratory process is found unsatisfactory with periodic monitoring, it may not be possible or desirable to retrospectively re-process those slides processed during the unsatisfactory period. No alternative solution has been available prior to this invention.
It is one motivation of the invention to automate a process that is currently carried out using subjective manual processes. It is another motivation of the invention to improve the quality and consistency of smear and slide preparation for the detection of disease processes.
In contrast to the prior art, the present invention provides a method and apparatus wherein slides and specimens are examined in an automated biological specimen screener such as the AutoPap 300 System made by NeoPath, Inc. of Redmond, Wash., U.S.A. The automated biological specimen screener measures, among other things, parameters of specimen collection quality, fixation quality, staining quality and mounting quality. These measures are objective and provide a consistent standard of evaluation. Rather than monitor periodically, an automated biological specimen screener made in accordance with the present invention measures a consistently updated most recent set of slides as part of the monitoring process. Continuous monitoring of process parameters provides the means to administer a short term and mid-term process tracking mechanism. The short-term tracking mechanism reports recent (that is, relative to mid-term) variations in the laboratory process that can be adjusted before adverse screening conditions occur. It also allows the laboratory to track variation patterns, providing the means to forecast adverse conditions which can occur if the parameters of the mid-term tracking mechanism fall outside acceptable limits. For example, keyed by slides which are increasingly borderline acceptable for the detection of disease processes, short-term tracking allows a laboratory to immediately detect changes in nuclear staining. These changes suggest the need to adjust staining solutions. The staining parameters for the short term tracking can be used to adjust a staining process in an automated fashion, before staining quality becomes unacceptable.